Black-clad activists smashed store windows and blocked traffic in Washington during U.S. President Donald Trump’s inauguration on Friday, and fought with police in riot gear who responded with tear gas and stun grenades.

About 500 people, some wearing masks, marched through the city’s downtown, using hammers to claw up chunks of pavement to smash the windows of a Bank of America branch and a McDonald’s outlet, all symbols of the American capitalist system.

The various protest groups scattered around the city chanted anti-Trump slogans and carried signs with slogans including "Make Racists Afraid Again," a play on the New York businessman-turned-politician’s "Make America Great Again" campaign slogan. The incident occurred about 90 minutes before Trump was sworn in at the U.S. Capitol a mile and a half (2.4 km) away.

Police detained dozens of people and said they had charged an unspecified number of people with rioting.

The group of detainees became a flash point after Trump was sworn in, when a crowd of several hundred that had formed to call for their release turned violent, with some throwing bottles and rocks at police, who responded with tear gas and stun grenades.

CNN reported that 90 people had been arrested.

Two police officers sustained minor injuries from people who were trying to avoid arrest, police said.

"The message I want to send is that Trump does not represent this country. He represents the corporate interests," said Jessica Reznicek, a 35-year-old Roman Catholic aid worker from Des Moines, Iowa, who was part of the protest but did not participate in the violence.

Not far from the White House, protesters scuffled with police, at one point throwing aluminum chairs at an outdoor café. Bob Hrifko, a member of the Bikers for Trump group in town to celebrate the inauguration, was struck in the face when he tried to intervene.

"I know, law and order and all that. We need more order. This ain’t right," said Hrifko, who was bleeding from a cut under his eye.

Activists race after being hit by a stun grenade while protesting against U.S. President-elect Donald Trump on the sidelines of the inauguration in Washington, U.S., January 20, 2017. REUTERS/Adrees Latif

CROWDS THIN

The number of people who turned out to view the midday swearing-in, on a gray day threatened by rain, appeared to be significantly smaller than the estimated 2 million who turned out for now-former President Barack Obama’s first inauguration in 2009.

Overhead video of the National Mall showed sections of the white matting laid down to protect the grass were largely empty.

More people were expected to be on hand when Trump and his entourage travel along Pennsylvania Avenue to the White House later Friday afternoon.

Earlier, liberal activists with a group called Disrupt J20 intermittently blocked multiple security checkpoints leading to the largest public viewing area for the inauguration. Several were led away by police.

Disrupt J20 protest organizer Alli McCracken, 28, of Washington, said the group was voicing its displeasure over Trump’s controversial comments about women, illegal immigrants and Muslims.

SYMPATHY RALLIES

Tensions were high on the streets of Washington, with scuffles breaking out between Trump supporters and opponents.

Trump supporters Chris and Karen Korthaus, who carried a life-size cardboard cutout of the former reality TV star, crossed paths with an anti-Trump crowd.

"A protester came over and ripped off the Don’s head," Karen Korthaus said as she showed a reporter a video of the incident. "We ran to a pizza shop and taped his head back on".

Members of Bikers for Trump assembled near the start of the route the new president will take to the White House to cheer the parade, shrugging off Trump opponents who briefly engaged them in a shouting match.

"They’re just trying to argue," said a member of the bikers group, Donald Gregory, 53, of North Carolina. "We finally have someone we can root for."

Trump’s inauguration drew reaction across the world.

In Tokyo, several hundred people, most of them expatriate Americans, protested against Trump. In London, activists draped a banner across the British capital’s iconic Tower Bridge reading "Build bridges not walls," a reference to Trump’s promise to wall off the U.S.-Mexico border.

But in Moscow, Russians hoping Trump will usher in a new era of detente with their country celebrated his inauguration. To the east, craftsman in the city of Zlatoust released a limited series of silver and gold commemorative coins, engraved with "In Trump We Trust."

The U.S. Secret Service, Washington police and other law enforcement agencies had about 28,000 officers in place to secure a roughly three-square-mile (7.8 square km) of downtown Washington.

Along the stretch of Washington where the rioters smashed windows, workers were beginning to clean up the debris.

"We’re just working, and the next thing you know, violence is coming our way," said Edwin Garcia, 26, a cook at an Au Bon Pain where three windows were shattered. "What was the point if they never got to where Trump is?"